(a) Field of the Invention
This invention relates to a system for actuating an elastomeric structure such as an elastomeric shutter.
(b) Description of the Prior Art
Closable openings are used on vessels for a variety of purposes. For example, as shown in U.S. Pat. No. 3,151,663 to Bohner et al., an inflatable closure apparatus is used to close an opening to a compartment in which a retractable wheel is stored. The closure apparatus has a plurality of inflatable tubes which are moved from a retracted position where the compartment is open to an extended position where the compartment is closed. A mechanical closure system having a plurality of links actuated by piston cylinder devices is used to move the inflatable tubes between the retracted and extended positions.
In the hull of a submarine vessel, closable openings are needed for the ejection of weapons, unmanned undersea vehicles, countermeasures, waste, and for the ingestion of water and unmanned undersea vehicles into the submarine. An elastomeric shutter system has been developed to act as closures for these openings. U.S. Pat. No. 5,419,232 to Curtis illustrates one such system in which an elastomeric shutter is drawn open using a cable system and a suitable attachment to the shutter. U.S. Pat. No. 5,450,807 to Moody illustrates yet another submarine closure system.
Under some circumstances, mechanical articulators may be an adequate approach to actuating a flexible surface, however other situations exist when the desired surface deformations are too complex to be produced by a series of pushing and pulling articulators or when the required articulation hardware cannot be fit into the available space surrounding the elastomeric part. Thus, an alternative actuation system is needed.
Inflatable tubes have been used in a variety of different environments for a variety of different purposes. For example, U.S. Pat. No. 2,404,801 to Hollerith illustrates an expander tube for a hydraulic brake which is arranged to expand outwardly upon being subjected to internal pressure by means of hydraulic fluid. U.S. Pat. No. 3,924,519 to England illustrates an actuator formed of an elastic tubing having a circumferential reinforcement therein and having a portion of the transverse periphery with longitudinal cords of tension resistant material along only one side of the tubing. In its relaxed state the device is substantially linear, but upon introduction of a pressurized fluid therein the tube curls about the side having the longitudinal reinforcing cords and upon release of the pressurized fluid the device returns to a substantially linear state. This actuator has utility in moving disabled or human handicapped limbs.
U.S. Pat. No. 3,464,322 to Pequignot illustrates a deformable diaphragm intended to produce impulsing or pumping effects in a fluid. The diaphragm is formed by a tube of elliptical section wound in a spiral with adjacent turns welded together and the outer edge being gripped in a support. The tube is connected to a source of fluid under pressure, the admission of which causes deformation of the tube and consequent inflation of the diaphragm.
U.S. Pat. No. 5,251,538 to Smith relates to an apparatus for handling a workpiece comprising a vessel that is longitudinally extensible and pressurizable, and a nonextensible and laterally flexible member on the vessel. The member constrains one side of the vessel to be nonextensible causing the vessel to bend in the direction of the nonextensible member when pressurized.
None of these actuation devices is well suited for operating an elastomeric structure, such as an elastomeric shutter system, for closing openings in the surface of a ship hull.